Surface cleaner

ABSTRACT

A surface cleaner having a cleaning head. The cleaning head has a deck and a skirt extending from the deck such that when the skirt is placed in contact with the surface to be cleaned, a cleaning volume is defined. The cleaning head has at least one vent port and at least one vacuum port formed therein. Nozzles are mounted in the cleaning volume for movement therein when fluid under pressure is supplied thereto and sprayed therefrom. A liquid supply system supplies the fluid under pressure to the nozzles so that the surface to be cleaned is effectively scrubbed by the fluid to produce a mixture of the fluid and contaminants loosened from the surface to be cleaned. A vacuum recycling system coupled to the vacuum port(s) draws high-pressure air through the vent port(s) and over the surface being sprayed with the liquid under pressure. The mixture of fluid and contaminants is suctioned through the vacuum port(s) and filtered to separate the fluid from the contaminants. The fluid so-separated is then discharged. The fluid has a boiling point lower than the temperature and atmospheric pressure in which the cleaner is operated.

FIELD OF THE INVENTION

The invention relates generally to a surface cleaning apparatus. More particularly, the invention relates to a self-contained surface cleaner that effectively scrubs a surface with a pressurized fluid, and reclaims the contaminants loosened from a surface during the cleaning thereof.

BACKGROUND OF THE INVENTION

A variety of industrial-strength surface cleaners are known in the prior art. In general, a pressurized cleaning fluid is sprayed onto a surface to loosen dirt, rubber, oil, grease, etc., that has been deposited on the surface during the use thereof. The loosened dirt and other contaminants are then vacuumed. Some surface cleaners filter out the dirt and other contaminants in order to reuse the cleaning fluid. Specific examples of prior art surface cleaners are noted below.

U.S. Pat. No. 3,959,010 discloses a surface cleaner having a spray/vacuum head attached to the front of a tractor and having mechanical systems mounted on a towed trailer. The spray/vacuum head has spray nozzles mounted in separate fore and aft compartments thereof. A central compartment positioned between the fore and aft compartments defines a vacuum chamber. Holes are provided in a bottom wall of the vacuum chamber adjacent the surface to be cleaned. Air vortexes are created at the holes as the vacuum is drawn therethrough.

U.S. Pat. No. 4,845,801 discloses a surface cleaning vehicle having a forward-mounted low-pressure sprayer, an aft-mounted high-pressure sprayer head and vacuum head mounted aft of the high-pressure sprayer for vacuuming up liquid and loose debris.

U.S. Pat. No. 5,331,713 discloses a surface cleaning vehicle having a front-mounted sprayer followed immediately by rotating brush heads. A squeegee and vacuuming assembly is mounted at the aft portion of the vehicle to vacuum up cleaning liquid and debris.

U.S. Pat. Nos. 5,287,589, 5,469,597 and 5,979,012 disclose surface cleaners having vehicle-mounted mechanical systems coupled by long hoses to either walk-behind cleaning heads or individual spray and vacuum wands. The walk-behind cleaning heads or wands must be manually moved/manipulated while the vehicle is frequently moved to a suitable support distance.

The Applicant's prior U.S. Pat. No. 6,381,801 discloses a self-propelled surface cleaning vehicle having a high-pressure sprayer to spray cleaning fluid or water to loosen dirt, rubber, oil, grease, paint, surface coatings, rust, etc., which has been deposited or formed on the surface. This cleaner reclaims the fluid and removed contaminants, and recycles the fluid to be used again.

However, each of these prior art surface cleaners are relatively large to accommodate the fluid storage, reclamation and recycling equipment. The need exists for a surface cleaner which is not as large and cumbersome as known cleaners and which is even more effective in reclaiming the contaminants removed from the surface being cleaned.

SUMMARY OF THE INVENTION

Accordingly, the present invention may provide a surface cleaner having improved cleaning capabilities with a reduced size for cleaning hard flat industrial surfaces such as ship decks, airport runways, streets, parking surfaces and industrial floors.

The present invention may also provide a surface cleaner that is totally self-contained and mobile.

The present invention may further provide a surface cleaner that can be operated by a single person.

The present invention may be used to remove debris and contaminants from a surface, or to remove rust, paint or other surface coatings.

The present invention may provide a surface cleaner that effectively scrubs a surface without the use of brushes or other types of surface-contacting scrubbing devices.

The present invention may still further provide a self-propelled surface cleaner that is easy to maneuver on a surface to be cleaned.

The present invention may also provide a surface cleaner that traps loosened surface contaminants in order to prevent any toxic exposure to the environment.

Other advantages of the present invention will become more obvious hereinafter in the specification and drawings.

BRIEF DESCRIPTION OF THE DRAWING FIGURES

FIG. 1 is a side schematic view of an embodiment of the self-propelled surface cleaner according to the present invention;

FIG. 2 is a front interior view of the surface cleaner's cleaning head taken along line 2--2 of FIG. 1;

FIG. 3 is an isolated side view depicting an embodiment in which the pair of nozzles are coupled to the rotating arm at an angled orientation;

FIG. 4 is a side view of a portion of the cleaning head taken along line 4--4 of FIG. 3 depicting the attachment of the sealing band to the cleaning head's skirt;

FIG. 5 is a schematic view of another embodiment of the drive train according to the present invention;

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring now to the drawings, and more particularly to FIG. 1, a self-propelled surface cleaner according to the present invention is shown and referenced generally by numeral 10. Surface cleaner 10 is a self-contained assembly for cleaning a surface 100 over which it can be driven. Such surfaces include, but are not limited to, runways, streets, sidewalks, parking surfaces, decks of ships and industrial floor areas.

Surface cleaner 10 includes a self-propelled vehicle having a frame 12, a drive train coupled to frame 12 that includes a transmission 14 coupled to rear wheels 18 (as shown) and/or front wheels 16. The drive system 15 is outline in the indicated dashed lines in FIG. 1. Controls for driving surface cleaner 10 and operating various systems thereon are provided in a driver/operator compartment 20 at the front portion of the vehicle. For reasons that will be explained further below, transmission 14 can be selectively coupled to either secondary drive or a combustion-engine motor 24 via an operator-positioned switch 26. For reasons that will be explained further below, the driving speed of surface cleaner 10 can be limited to a maximum speed by coupling a speed limiter or governor 34 to transmission 14. Another option is to dictate a constant driving speed of surface cleaner 10 by coupling a speed controller 36 to transmission 14.

Combustion-engine motor 24 can be any motor that runs on a combustible fuel such as gasoline, diesel fuel, propane gas, etc. The transmission 14 may be any device which translates power to the driving wheels, such as a conventional mechanical transmission, electric motor, hydraulic motor, gas (air) motor, etc., or combinations thereof.

In one embodiment of the drive train 15, an electric motor 22 can be powered by one or more batteries 28 or by a DC current-producing alternator 30. More specifically, alternator 30 is coupled mechanically to combustion-engine motor 24 and electrically to a switch 32 that is selectively positioned to couple either batteries 28 or alternator 30 to electric motor 22. In this way, even if batteries 28 run low during the cleaning operation, power for electric motor 22 can simply be switched over to alternator 30 which is turned by combustion-engine 24. An AC voltage generator 38 is also mechanically coupled to combustion-engine motor 24 to produce an AC voltage for use by various electrically-powered elements onboard surface cleaner 10 as will be explained further below.

FIG. 5 depicts another preferred embodiment of the drive system 15, utilizing hydraulics instead of electric power. In this embodiment the combustion-engine motor 24 is connected to a hydraulic pump 23 which is selectively coupled to the transmission 14. In this embodiment the transmission 14 for the hydraulic pump 23 is a hydraulic motor. As in the previous embodiment, the combustion-engine motor 24 is also coupled to an alternator 30 and/or a generator 38 which provide electric power to batteries 28 and to other electrical devices. Likewise, switch 26 selectively couples the transmission to the hydraulic pump 23 or the combustion-engine motor 24. A speed limiter 34 and speed controller 36 can also be coupled to the transmission 14. In this embodiment the speed limiter 34 and speed controller 36 may comprise a hydraulic valve system which regulates the pressure and the amount of hydraulic fluid delivered to the transmission 14 from the hydraulic pump 23.

A cleaning head 40 is mounted to surface cleaner 10 by means of, for example, an arm 42 pivotally attached to frame 12 at pivot point 44. Arm 42 can be manually pivoted or pivoted via a motorized force to raise/lower cleaning head 40 and set a forward-to-rear pitch angle of cleaning head 40 relative to surface 100.

Cleaning head 40 is defined by an inverted tray shape having a top or deck 46 and a peripheral side skirt 48 that extends down from deck 46 when cleaning head 40 is positioned over surface 100 as shown. In use, when cleaning head 40 is placed in contact with surface 100, (i.e., a sealing band 70 contacts surface 100), a cleaning volume 50 is defined by the volume of air space bounded by deck 46 on its top, skirt 48 (to include band 70) on its sides and surface 100 at its bottom. Preferably at the forward portion of cleaning head 40, one or more vent ports 54 are provided. Preferably at the rear portion of cleaning head 40, one or more vacuum ports 56 are provided. By way of convention, the terms “forward” and “rear” as used herein are relative to normal forward motion of surface cleaner 10, i.e., front wheels 16 leading back wheels 18.

Ports 54 and 56 are preferably formed in deck 46 and allow outside air to communicate with cleaning volume 50. The area defined by ports 54 should be approximately equal to the area defined by port(s) 56. However, the shape or number of ports 54 or 56 is not a limitation of the present invention. An open-ended prior duct 60 can be attached to deck 46 to effectively extend the height at which each port 54 communicates with the outside air. The function of duct 60 will be explained below.

Alternatively, the skirt 48 may comprise a series of brushes or bristles, and the spaces between the brushes/bristles may function as the vent ports 54.

Referring additionally to FIG. 2 which depicts a front interior view of cleaning head 40 taken along line 2--2 in FIG. 1, a pair of side-by-side arms 62 and 64 are rotatably mounted to deck 46 by means of spindles (or otherwise known as swivels) 62A and 64A, respectively. Each combination of spindles and arm (e.g., spindle 62A and arm 62) is also a conduit for delivering a fluid supply to nozzles 66A/66B (mounted on arm 62) and nozzles 68A/68B (mounted on arm 64). Arms 62 and 64 are sized so that nozzles 66A/66B and 68A/68B experience movement within cleaning volume 50 between ports 54 and 56. The nozzles 66A/66B and 68A/68B are preferably directed straight down towards the cleaning surface to maximize the cleaning impact of the fluid on the surface. In such an embodiment the spindles must be rotated by some rotation means 61. The rotation means 61 may be directly or indirectly powered by any conventionally known rotational power source including but not limited to a combustion engine, electric motor, hydraulic motor, gas motor (air motor), etc.

Alternatively, as shown in FIG. 3, the spindle 62A and arm 62 may be self-propelled by the force of the fluid exiting the nozzles 66A, 66B, 68A and 68B, at an acute angle. Each of the nozzles is directed towards surface 100 at an acute angle with respect to a surface-extending vertical line such that when fluid is sprayed therefrom, arms 62 and 64 rotate parallel to deck 46 on their respective spindles. For example, as illustrated in FIG. 3, nozzles 66A and 66B are directed at opposite acute angles φ relative to an imaginary vertical line 102 that is perpendicular to surface 100. Acute angle φ is typically in the range of approximately 0-30°.

As mentioned above, attached to the lower periphery of skirt 48 is a band 70 of flexible material that forms a seal with surface 100. Band 70 is a strong but flexible material that can withstand abrasion forces developed as cleaning head 40 moves over surface 100. A material that performed well in testing of surface cleaner 10 is a multi-layered material having alternating layers of rubber and nylon. This material is available commercially from a variety of rubber manufacturers such as B.F. Goodrich and Goodyear.

Referring now to FIG. 4, band 70 is mounted to skirt 48 using a plurality bolts/screws 72. Band 70 has elongated slots 74 formed therethrough to receive bolts/screws 72. The use of elongated slots 74 allows band 70 to be lowered as its bottom edge 70A becomes worn/damaged. This effectively increases the useful life of band 70.

Attached to the forward end of cleaning head 40 are a plurality of spaced-apart wheel assemblies, one of which is illustrated in FIG. 1 and referenced generally by numeral 80. The wheel assemblies support-cleaning head 40. Further, by making the height of each wheel assembly 80 independently adjustable, the side-to-side pitch of cleaning head 40 can be adjusted. In general, a wheel assembly 80 includes a fixed support 82 and an adjustable height support 84 coupled to a wheel 86. The particular configurations of support 82 and 84 are not limitations of the present invention.

Coupled to cleaning head 40 are a fluid delivery system and a vacuum system, both of which are mounted on frame 12. Alternatively, the fluid delivery system and/or vacuum system may be mounted on a separate trailer. Referring again to FIG. 1, the basic elements of the fluid delivery system are contained within dashed-line box 90 and the basic elements of the vacuum system are contained within dashed-line box 92. Electricity for various elements of systems 90 and 92 is provided by generator 38, alternator 30 or batteries 28.

One advantage of mounting the fluid delivery system 90 and vacuum system 92 on a separate trailer is that the surface cleaner could then also be easily used with conventional water or other cleaning liquid delivery and vacuum systems mounted on another trailer. Thus, either delivery and vacuum system could be used depending on the conditions and choice of the user. The trailer with mounted fluid delivery system and vacuum system 92 may be pulled behind the driven surface cleaner, thus allowing the surface cleaner to be very versatile and mobile.

Fluid delivery system 90 includes a storage tank 902 which can be baffled at 904 to prevent/minimize sloshing forces when surface cleaner 10 is moving. A high-pressure pump 906 is coupled to tank 902 to draw fluid therefrom and pump same under high pressure to spindles 62A/64A. Although not shown for clarity of illustration, pump 906 is typically a mechanically-driven pump that would be coupled to combustion-engine motor 24 as would be well understood in the art.

The pressurized fluid is supplied at 901 to nozzles 66A/66B and 68A/68B via spindle 62A/arm 62 and spindle 64A/arm 64, respectively. Each arm rotates within cleaning volume 50 as fluid is sprayed onto surface 100.

Vacuum system 92 includes a vacuum 920 having its blowing vent side vented at 922 and its suction side coupled to a vacuum tank 924. Vacuum tank 924 is a sealed tank ported at 926 and 928. Ports 926 and 928 should define approximately equal areas. Port 928 has a larger-particle filter 930 coupled thereto. Filter 930 resides in the air space of vacuum tank 924, and will be explained further below. Port 926 is coupled via hose 942 to vacuum port(s) 56.

The present surface cleaner 10 most notably differs from prior surface cleaners by the type of cleaning fluid which is used. While the prior surface cleaners use water or some other cleaner comprising mostly water, the present invention uses a cleaning fluid having a very low boiling point, and which evaporates very quickly when exposed to outside atmospheric conditions. The preferred cleaning fluid of the present invention is nitrogen, although other fluids may be used. Nitrogen is preferred because it is readily available and economical, non-toxic to the environment, and does not pose any fire, explosive, toxic or other hazard to an operator.

The term “fluid” or “cleaning fluid” as used throughout this specification is defined as encompassing any material either in a liquid or gaseous state. These terms are also defined to encompass those materials, such as carbon dioxide, which evaporate directly from a solid state to a gaseous state. Such materials may be stored in a solid state, but in use are in a gaseous state; it is assumed that when stored at least some part of the material is in a gaseous state, or in other words in fluid form.

Preferably, the cleaning fluid is stored in a liquid state, under pressure in tank 902. The cleaning fluid is maintained under pressure until the cleaning fluid is sprayed from nozzles 66A/66B and 68A/68B. As the cleaning fluid exits the nozzles 66A/66B and 68A/68B it is quickly subjected to atmospheric conditions and begins to evaporate. The cleaning fluid contacts the surface 100 in a liquid state at a very cold temperature. For example, liquid nitrogen has a boiling point of −195.8° C. under atmospheric pressure at sea level. Any contaminants on the surface 100 are almost instantaneously frozen (flash frozen). The combination of the very cold temperature and force at which the cleaning fluid strikes the surface causes the contaminants to lift from the surface 100 and break into small particles, which become entrained in the cleaning fluid and incoming air mixture 202.

In operation, surface cleaner 10 has tank 902 filled with cleaning fluid and may be driven to a site to be cleaned. When driving to a site, switch 26 will normally be positioned to couple combustion-engine 24 to transmission 14. Once surface cleaner 10 is in position to begin cleaning, switch 26 is positioned so that electric motor 22 OR hydraulic pump 23 is coupled to transmission 14. Combustion-engine motor 24 continues running to turn alternator 30 and generator 38, as well as provide the mechanical drive for elements such as pump 906. Cleaning head 40 is lowered onto surface 100 with its front-to-rear and side-to-side pitch being set to accommodate surface 100. Systems 90 and 92 are turned on and surface cleaner 10 is driven over surface 100.

The cleaning fluid under pressure is sprayed from nozzles 66A/66B and 68A/68B on rotating arms 62 and 64, respectively, between ports 54 and 56 as described above. The cold, pressurized fluid loosens solid debris and other contaminants from surface 100. A vacuum force created by vacuum system 92 is applied through hose 942 to port(s) 56. The suction force from this vacuum draws outside air into cleaning volume 50 via duct(s) 60. The use of ducts 60 prevent fluid sprayed into cleaning volume 50 from escaping therefrom via port(s) 54. The resulting fluid flow into and through cleaning volume 50 is illustrated at 200. By placing port(s) 54 and 56 at the respective forward and rear portions of cleaning volume 50, a high-pressure fluid flow is drawn over surface 100 in the area where high-pressure cleaning fluid is being sprayed. This large area of high-pressure fluid flow serves to not only pick up the loosened debris/contaminants, but also frees debris/contaminants partially loosened by the high-pressure cleaning fluid spray. Placing ports 54 and 56 in the top of cleaning volume 50 (i.e., in deck 46) has the further advantage of allowing the downward rush of air passing through duct(s) 60 and port(s) 54 to strike surface 100 to aid in loosening contaminants from surface 100. The resulting mixture 202 of fluid, air and loosened debris/contaminants is drawn into hose 942 and delivered to vacuum tank 924.

Mixture 202 is filtered by particle filter(s) 930 where solid particles and liquids are trapped and retained in the tank 924. Preferably, the tank 924 has a horizontally extending screen 923 on which solid particles will collect and liquids may pass through to collect in the lower portion of the tank 924 where the collected liquids may be drained through a drain port 925. The filtered fluid, which is now all in a gaseous state, and air mixture are vented at 922 to the outside atmosphere.

At the drain port 925 there may be provided a valve 935. The valve may be a three-way valve having a first position in which the valve 935 is closed, a second position in which the valve 935 directly discharges the liquid collected in the lower portion of the tank 924, and a third position in which the liquid is directed through a filtering process. In this further liquid filtering process the liquid passes through pump 934 and one or more filters 938. The filtered liquid could then also be passed through an oil separator 940 if necessary. The relative positions of the pump 934 and the valve 935 may also be switched so that the pump 934 is used regardless of whether the liquid is being directly discharged from the tank 924 or filtered.

During the cleaning process, surface cleaner 10 is driven under the power of electric motor 22 or hydraulic motor 33 because of the smoother delivery of power to transmission 14 as compared to combustion-engine motor 24. For optimum cleaning, cleaning head 40 should move at a relatively constant speed over surface 100. This constraint is simplified for an operator by powering transmission 14 via electric motor 22. For greater precision, a consistent speed could be maintained automatically by use of speed control 36. Furthermore, optimum cleaning is obtained by assuring that cleaning head 40 is positioned over each area of surface 100 for a certain period of time. This is achieved by not driving surface cleaner 10 to quickly over surface 100. Once again, while this quality control measure can be left up to the operator, speed limiter 34 can be coupled to transmission 14 during the cleaning operation to assure that the maximum (optimum cleaning) speed for a particular surface is not exceeded. For safety reasons, the use of speed limiter 34 may be preferred to speed control 36.

Liquid nitrogen may be stored and maintained in tank 902 under 80 pounds per square inch (psi) of pressure. The liquid nitrogen is sprayed out of the nozzles 66A/66B and 68A/68B at up to 55,000 psi. Most cleaning operations will require the cleaning fluid be sprayed at between 3,000 and 6,000 psi. Removal of paint and other coatings may require that the cleaning fluid be sprayed at higher pressures.

A typical cleaning operation would require approximately 400 gallons of liquid nitrogen for each hour of operation, for a 72″ path covered by the cleaning head 40. This amount of liquid nitrogen would be enough to clean approximately 20,000 to 25,000 square feet of a surface 100.

In contrast, a similar surface cleaner using pressured water would require approximately 800 gallons of water for each hour of operation which additionally would need to be filtered, stored before and after use, and further reclaimed and recycled. The surface cleaner 10 of the present invention thus may be made much smaller and lighter, and may even be made small enough so that it may be incorporated into a user-propelled package for smaller cleaner operations.

Furthermore, a separate cleaning head 40 and wheel assembly 80 having a smaller cleaning path may be incorporated into a smaller package, easily maneuvered by a user, and operatively connected to the fluid delivery system 90 and vacuum system 92 by hoses. This would allow a user to clean hard to reach places with the smaller surface cleaner package which are not accessible to a larger self-contained surface cleaner package.

Larger, self-propelled surface cleaners 10 may also incorporate a fluid condenser 905 into the fluid delivery system 90 which continuously refills and maintains liquid nitrogen or other fluid in the tank 902.

The advantages of the present invention are numerous. Improved surface cleaning is achieved by a uniquely-designed cleaning head that uses both a high pressure cleaning fluid and a uniquely directed vacuum flow to remove the maximum amount of debris/contaminants from a surface using only a very cold and highly pressurized fluid having a very low point. The surface cleaner is self-contained and may be self-propelled so that it can be efficiently operated by one person. There is no contaminated cleaning water which needs to be reclaimed for reuse. Further, since the spray/vacuum operation is contained within a single cleaning head, there is no toxic runoff generated by the cleaning operation. The surface cleaner can be propelled smoothly by an electric or hydraulic motor for optimum cleaning while simultaneously using a combustion-engine motor to charge batteries and drive various mechanical systems. The overall weight, size and complexity of the surface cleaner is greatly reduced.

Although the invention has been described relative to a specific embodiment thereof, there are numerous variations and modifications that will be readily apparent to those skilled in the art in light of the above teachings. It is therefore to be understood that, within the scope of the appended claims, the invention may be practiced other than as specifically described. 

1. A surface cleaner, comprising: a cleaning head having a deck and a skirt extending from said deck wherein, when said skirt is placed in contact with a surface to be cleaned, a cleaning volume is bounded by said deck, said skirt and the surface to be cleaned; said cleaning head having at least one vent port and at least one vacuum port formed therein; at least one nozzle mounted to said deck within said cleaning volume when fluid under pressure is supplied thereto and sprayed therefrom; a fluid supply system for supplying said fluid under pressure to said nozzles wherein the surface to be cleaned is effectively scrubbed by said fluid to produce a mixture of said fluid and contaminants loosened from the surface to be cleaned; and a vacuum system coupled to said at least one vacuum port for suctioning said mixture, filtering said mixture to separate said fluid from said contaminants and discharging said fluid so-separated; wherein said fluid has a boiling point lower than the temperature and atmospheric pressure in which the surface cleaner is operated.
 2. The surface cleaner as in claim 1 wherein said fluid is nitrogen.
 3. The surface cleaner as in claim 1 having at least one drive system for propelling said surface cleaner on said surface to be cleaned.
 4. The surface cleaner as in claim 1 wherein said at least one vent port and said at least one vacuum port are formed in said deck.
 5. The surface cleaner as in claim 1 wherein said skirt at least partially comprises a series of bristles having spaces therebetween, and said at least vent port comprises the spaces between said bristles.
 6. The surface cleaner as in claim 1 wherein the area defined by said at least one vent port is approximately equal to the area defined by said at least one vacuum port.
 7. The surface cleaner as in claim 1 further comprising an open-ended duct extending from each said vent port and away from said cleaning volume.
 8. The surface cleaner as in claim 1 wherein said skirt includes a flexible seal for contacting the surface to be cleaned.
 9. The surface cleaner as in claim 8 wherein said flexible seal comprises a multi-layered material having at least one layer of rubber and at least one layer of nylon.
 10. The surface cleaner as in claim 8 wherein said flexible seal is mounted for adjustable positioning relative to said deck.
 11. The surface cleaner as in claim 1 further comprising means for adjusting a forward-to-rear pitch of said cleaning head relative to the surface to be cleaned.
 12. The surface cleaner as in claim 1 further comprising means for adjusting a side-to-side pitch of said cleaning head relative to the surface to be cleaned.
 13. The surface cleaner as in claim 3 wherein said at least one drive system comprises: an electric motor; a combustion-engine motor; a drive train; and means for selectively coupling one of said electric motor and said combustion-engine motor to said drive train to propel said surface cleaner.
 14. The surface cleaner as in claim 13 further comprising: at least one battery serving as a first source of electricity; an alternator coupled to said combustion-engine motor wherein operation of said combustion-engine motor causes said alternator to serve as a second source of electricity; and means for coupling one of said first source and said second source to said electric motor.
 15. The surface cleaner as in claim 3 further comprising a speed limiter coupled to said at least one drive system for setting the top speed of said surface cleaner.
 16. The surface cleaner as in claim 3 further comprising a speed control coupled to said at least one drive system for maintaining a selected constant speed of said surface cleaner.
 17. The surface cleaner as in claim 3 wherein said at least one drive system comprises a combustion-engine motor; a hydraulic pump; a drive train; and means for selectively coupling one of said hydraulic pump and said combustion-engine motor to said drive train to propel said surface cleaner.
 18. The surface cleaner as in claim 1 further comprising at least one mounting arm rotatably mounted to said deck between said forward portion and said rear portion for rotation within said cleaning volume in a plane substantially parallel to said deck, each of said mounting arms having at least one nozzle mounted thereon wherein said mounting arms rotate when said liquid under pressure is sprayed from said nozzles.
 19. The surface cleaner as in claim 1 wherein said fluid supply system comprises: a tank for storing said fluid; and a pump coupled to said tank for pumping said fluid therefrom under pressure to said nozzles.
 20. The surface cleaner as in claim 1 wherein said vacuum system comprises: a vacuum tank coupled to said at least one vacuum port; a filter means mounted in said vacuum tank for filtering said mixture and wherein said contaminants are deposited in said vacuum tank; and a vacuum source coupled to said vacuum tank for suctioning air and fluid in a gaseous state from said vacuum tank to maintain a suction force at said at least one vacuum port.
 21. The surface cleaner as in claim 18 further comprising a rotation means for rotating said mounting arms.
 22. The surface cleaner as in claim 19 further comprising a fluid condenser coupled to said tank for supplying fluid to said tank.
 23. The surface cleaner as in claim 18 wherein at least one nozzle is directed towards the surface to be cleaned at an acute angle with respect to the vertical.
 24. The surface cleaner as in claim 1 wherein at least one of said fluid supply system and said vacuum system are mounted on a separate trailer.
 25. The surface cleaner as in claim 1 comprising a secondary cleaning head mounted separate from said surface cleaner and operatively connected to said fluid supply system and vacuum system.
 26. The surface cleaner as in claim 20 further comprising a horizontally extending screen in said vacuum tank on which solid contaminants are collected, and through which liquid may pass and collect in a lower portion of said vacuum tank.
 27. The surface cleaner as in claim 26 further comprising a drain port in said lower portion of said vacuum tank.
 28. The surface cleaner as in claim 27 further comprising a valve connected to said drain port through which liquid is selectively discharged for further filtering.
 29. A method of cleaning a surface comprising the steps of: providing a surface cleaner on a surface to be cleaned, comprising: a cleaning head having a deck and a skirt extending from said deck wherein, when said skirt is placed in contact with the surface to be cleaned, a cleaning volume is bounded by said deck, said skirt and the surface to be cleaned; said cleaning head having at least one vent port and at least one vacuum port formed therein; at least one nozzle mounted to said deck for movement within said cleaning volume when fluid under pressure is supplied thereto and sprayed therefrom; a fluid supply system mounted on said cleaner; and a vacuum recycling system mounted on said cleaner and coupled to said at least one vacuum port; wherein said fluid has a boiling point lower than the temperature and atmospheric pressure in which the surface cleaner is operated; supplying said fluid under pressure from said fluid supply system to said plurality of nozzles wherein the surface to be cleaned is effectively scrubbed by said fluid to produce a mixture of said fluid and contaminants loosened from the surface to be cleaned; suctioning said mixture by said vacuum system; filtering said mixture to separate said fluid from said contaminants; and discharging said fluid so-separated.
 30. The method as in claim 29 wherein said fluid is nitrogen.
 31. The method as in claim 29 further providing at least one drive system for said surface cleaner. 